1. Field of the Invention
The present invention relates to a data recorder.
2. Description of the Related Art
In recent years, there are techniques in which a speedometer for measuring the vehicle speed of a running motor vehicle and an accelerometer for measuring the acceleration thereof are placed on the vehicle so that states of the vehicle such as vehicle speed, acceleration and the like are recorded in a data recorder when an acceleration in a speed reducing direction (hereinafter, referred to as deceleration) that is generated at the time of an accident exceeds a certain value. By analyzing the states of the vehicle recorded in the data recorder, the analysis of the cause of the accident which involved the vehicle is helped. An example of such a related data recorder is disclosed in JP-A-10-63905 below.
In the related data recorder disclosed in JP-A-10-63905, however, since whether or not vehicle states are recorded is determined mainly by deceleration, in the event that an accident occurs due to a sudden start of a vehicle, the vehicle states are not recorded due to deceleration being small, and when it is set to store vehicle states at lower decelerations, the data recorder is activated to record vehicle states even by impact generated when the vehicle runs over bumps in the road.
In addition, in recent years, electronics have been adopted more and more in motor vehicles, and in many cases, a throttle of an engine, for example, is controlled electrically by an ECU. In particular, in electric vehicles, motors which acts as prime motors are controlled electrically completely. Because of this, it is difficult to determine whether a sudden start of the vehicle was triggered by a malfunction of the motors due to abnormal conditions occurring in the electrical system or an erroneous operation by the driver.